REACTIONS OF MELANOPHORES OF AMBLYSTOMA 



245 



when the melanophores are contracted or when they are scarce. 

 Figure 6 is given to show this, where, it will be admitted, it has 

 very much the appearance of a brow-spot or " Scheitelfleck " 

 and might be taken for such. 



From reading over the literature one is soon forced to the con- 

 clusion that it seems doubtful whether a parietal organ in any 

 Urodele could have an influence on the reactions of the melano- 



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Fig. 4 The anterior end of a sagittal section of the head of a 14.5 mm. larva. 



phores, and this particularly for the reason that a parietal organ 

 as such does not exist. There seems to be in all a small epiphysis 

 (Studnicka '05, and Warren '05). Nevertheless, although there 

 is no parietal organ and only a small epiphysis, there was still 

 the chance, considering the results obtained by von Frisch ('11), 

 that in this region of the brain there might be a 'center' the 

 stimulation of which would have an inhibitory influence on the 

 melanophores. 



